Simple tests allowing the quality of the vision of an individual to be evaluated under particular luminance conditions, and in particular when this luminance is low, or even very low, do exist.
It will be recalled that mesopic vision corresponds to vision of a scene the luminance of which is comprised between 3 and 10 cd/m2, and scotopic vision corresponds to vision of a scene the luminance of which is below 0.001 cd/m2.
Existing digital screens are unable to manage a display with such low luminance levels. Specifically, to reconstruct the conditions of a night scene, it is necessary to decrease the brightness of the screen to a lower level than manufacturers currently allow via their pages for parameterizing screen brightness.
Currently, the tests used to examine an individual's perception of contrast are carried out with pieces of apparatus employing characters to be viewed, these characters possibly for example being represented by a text and/or figures printed on transparent films. However, these pieces of apparatus have two limitations:                1—In order to test a maximum number of contrasts with a given plate, only a few characters are displayed with a given contrast level, and the various test configurations usable to test the vision of an individual are greatly limited;        2—To remedy the preceding limitation, it is necessary to multiply the number of test plates in order to allow a multiplicity of configurations usable to evaluate the vision of the individual to be achieved.        
Two major drawbacks result from these limitations, namely, on the one hand, the additional costs associated with the multiplication of the test plates and with the manufacture thereof, and, on the other hand, the substantial bulk associated with the multiplication of the test plates. In addition, in a technology involving a drum around which the test plates are placed, there remains less space for other types of tests.